I heard that the 3.5mm jack has limits that are being reached by some high-end headphones. I can't exactly recall, but I think it may have had something to do with no power for an external mixer or something?

Whatever it is, the solution that some headphones were using was the thunderbolt port on iPhones.

Does anybody know why they would be doing this?

And as another point of interest - is there a reason the 3.5mm jack would be phased out in the following decades?


There could be a limit on the amount of power that can be transmitted because of the common-ground/return circuit topology forced by the standard TRS pinout. It is much easier to get higher power from a balanced load where you can drive it diferentially. That allows driving each side of the voice-coil with the opposite polarity. A common method of increasing power output in voltage-limited circuits (such as battery-operated gear.)

Dunno what kind of "external mixer" you could be talking about?????

Apple is rumored to be planning on dropping the standard 3.5mm TRS or TRRS jack on future products. Presumed reasons include: Much easier to make the device water-resistant or even water-proof if you don't have any deliberate holes in the envelope. No tangly wires for the user to deal with. And last (but probably not least) better control over Rights Management to make it harder to copy program content.

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    Great points, I think you're right with the power limit. As for the mixer, I think it might have been something unique to a certain set of headphones. Either way, thanks for your insights and the early reply – Zarocross Jun 20 '16 at 14:33

The recent rise in discussion regarding the limitation of the 3.5mm jack, so far as audio quality is concerned, is more or less pure marketing.

The 3.5mm jack, while not the greatest connector in the world, is more than capable of carrying the current needed by headphones. The only technical limitation there is that due to the common ground, it is not possible to use a bridged output configuration for the headphone amplifier.

Now some informed speculation as to why Apple would like to eliminate the headphone jack:

1) They would like to make money licensing the right to sell Apple compatible headphones and audio adapters.

2) They would like to reduce their manufacturing cost by eliminating the DAC and headphone amp from the phone, passing them on to the consumer who will have to pay for them along with the overpriced and non-interoperable headphones and audio interfaces they will now have to buy.

3) They would like to make deals with car makers and accessory makers to marginalize analog connections as well as non-proprietary digital connections, so as to inconvenience the users of non-Apple products and make Apple products more appealing by comparison.

4) That their partner Intel developed Thunderbolt along with Apple, and that Intel holds intellectual property in this interface technology as well as in USB type C, may have a hand in this from a business perspective.

Thunderbolt is soon to start using a USB type C connector as well.

5) AND YES.. it opens the door for super-high-quality portable external DACS to be used easily, but they can do that now, without eliminating the jack.. for the few people who would actually use them with their portable devices. They would like you to think that this is their primary goal but it is not. If it was, they'd be supporting that via OTG already.

In summary, if/when this change takes place, the difference in quality will be if anything a net loss, since most headphone manufacturers will use cheap DACs in their products. Since headphones break often and DACs usually last the life of the phone, it makes far more sense for the DAC to be located in the phone.

  • There have been no chips from Intel in IPhone products to date. Future models may include Intel modem chips in order for Apple to diversify its supplier base. Doesn't seem to support very well (#4) as a theory. Source: bloomberg.com/news/articles/2016-06-10/… – Richard Crowley Jun 21 '16 at 23:16
  • It would have been more accurate for me to say that Intel developed the interface with Apple and has an intellectual property stake in it: en.wikipedia.org/wiki/Thunderbolt_%28interface%29 – little_birdie Jun 21 '16 at 23:21
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    I wouldn't put it past Apple to make hay out of "super-high-quality DACS" as an "advantage". But it is a laughable "feature" Considering that the source is compressed MP3 (or AAC, etc.) audio data, it is like serving up dog food in a silver chalice. – Richard Crowley Jun 21 '16 at 23:26
  • I see complete elimination of electrical connections in the future. If they can get rid of the Tunderbolt connector then they don't need ANY holes in the case and they can make it much more water-resistant. We are nearly there with wireless charging and NFC and WiFi for data. – Richard Crowley Jun 21 '16 at 23:29
  • As an audio professional (this is a pro audio stackexchange is it not??), Thunderbolt headphones would be worthless to me, as would any portable device that lacked either an S/PDIF or an analog output. – little_birdie Jun 21 '16 at 23:34

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